Recently, an Intelligent Power Module (IPM) has attracted the attention. This Intelligent Power Module is produced by modularizing a protection circuit against abnormality such as an overcurrent of a semiconductor device, a short-circuit, a voltage drop of a control power supply, and overheating of a chip temperature as one electronic component together with the semiconductor devices (power transistors such as IGBTs and MOSFETs) and their driving circuits.
There has also been advocated that an alarm signal output circuit, which outputs a pulse signal configured to form an alarm signal with a predetermined pulse width according to a kind of abnormality detected at each protection circuit, and a notification signal output circuit, which outputs one pulse equivalent to the set pulse width as a protected operation notification signal when the pulse signal is output from this alarm signal output circuit, are incorporated into an Intelligent Power Module in addition to a plurality of protection circuits each detecting such abnormalities (for example, see PTL 1).
Providing such discrimination circuit outputting the alarm signal allows discriminating a kind of abnormality occurred in a semiconductor device by detecting the pulse width of the alarm signal on a control device side controlling a driving device, for example, an inverter control device.
However, there is a problem that only outputting the protected operation notification signal by one pulse as described above cannot detect that abnormality has been solved even when the abnormality of the semiconductor device has been solved. Therefore, to avoid the above-described defect beforehand, this applicant has advocated a driving device of semiconductor device that outputs an alarm signal with a predetermined width with which an abnormal cause is identifiable when the abnormal cause occurs at preset time intervals and outputs an alarm release signal with a pulse with different from that of the alarm signal width when the abnormal cause is solved and the output of the alarm signal is terminated to facilitate discrimination of the alarm signal and the detection of the solution of the abnormality (see PTL 2).